Donna may have been joking, but The Doctor suspected that must be exactly where they were headed, not to mention exactly where they wanted to go.

"But why the escort?" he mumbled under his breath, squeezing the back of his neck as if it might somehow squeeze out the answers.

"Is it us that they want...or CrySS?" Donna whispered. "That's the only difference. They attacked us...but they're leading her. I mean...yeah?"

"Of course!" The Doctor looked up at Donna, lowering his voice to match. "Donna,you're brilliant! Crystal-powered sentient ship. Crystal-powered! Crystal as in the Crystal from these ranges. They wouldn't destroy her if they're protecting the Ranges, she's practically a part of them."

The ship suddenly bumped and rattled. "Turbulence," CrySS assured them. "We are entering a cave and there are wind currents around the opening." As CrySS spoke, the silver darts that had been escorting them so far, fell back to follow them instead. There was only one way for CrySS to go now... straight into the heart of the mountain.

Jenny petted the wall of the ship as the darts fell back, absently trying to soothe CrySS while listening to her dad and Donna figuring this situation out. They were absolutely brilliant, and she'd bet that CrySS being powered by crystal from the Ranges was part of the reason the darts were escorting rather than attacking.

After CrySS had navigated the turbulence at the entrance to the cave, Jenny narrowed her eyes as she looked out. It wasn't a normal tunnel they were flying in; or rather, it wasn't a natural tunnel now. It definitely showed signs of cutting, and she decided to point it out to everyone in case they were missing it. "Dad, Donna, Ianto - look at the walls. I'll bet we're in the mine, and whatever is behind the darts is further in. Probably got woken up when they dug too deeply."

The mine shaft went on for another quarter-kilometer, unerringly straight and easy for CrySS to fly down. It ended finally in a mutilated cavern, the evidence of destroyed and half-mined crystal stalactites and stalagmites littering the ground around abandoned mining equipment. There weren't any visible corpses, nor any noticeable bloodstains, but no one had left the safety of CrySS's passenger compartment yet, either. The darts, now that there was room, had clustered around CrySS once more, blocking off the view again and leading CrySS onward through the devastation.